Decades: 1190s 1200s 1210s 1220s 1230s - 1240s - 1250s 1260s 1270s 1280s 1290s
Years: 1240 1241 1242 1243 1244 - 1245 - 1246 1247 1248 1249 1250
Births
Deaths
... times an exponential function of time. The exponential function thus solves the basic differential equation <math>{dy \over dx} = y</math> and it is ...